The Bank of Russia acted quickly to shield the nation’s $1.5 trillion economy from sweeping sanctions that hit key banks, pushed the ruble to a record low and left President Vladimir Putin unable to access much of his war chest of more than $640 billion.

The central bank more than doubled its key interest rate to 20%, the highest in almost two decades, and imposed some controls on the flow of capital. It was part of a barrage of announcements that eventually restored some calm after a rout that pushed some Russian Eurobonds into distressed territory last week.

“The Bank of Russia will be very flexible in using all necessary instruments,” Governor Elvira Nabiullina said in brief televised remarks in Moscow.